Electric-arc lamp.



No. 727,714. v111111111211MA1 12, 1903.

E. THOMSON. ELECTRIC ARG LAMP.

APPLIUATIONhPILED 00T. 26, 1901.

H0 MODEL.

WM Elim Thomeon.

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UNITED STATES Patented May 12, 1903.

PATENT OEEICE.

ELIHU THOMSON, OF SWAMPSCOTT, MASSACHUSETTS, ASSIGNOR TO GEN- ERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELECTRIC-ARC LAMP.

SPECIFICATION forming part of Letters Patent N o. 727,714, dated May 12, 1903.

Application filed October 26,1901. Serial No. 80,044. (No model.)

To all whom t iai/Cty concern.-

Beit known that I, ELIHU THOMSON, a citizen of the United States, residing at Swampscott, county of Essex, State of Massachusetts, have invented certain new and useful Improvements in Electric-Arc Lamps, of which the following is a specification.

My present invention relates to improvements designed more especially for use in connection with direct-current arc-lamps, although not necessarily limited to use in this relation only.

The invention has for its object the production of an arc-lamp in which the arc-regulating mechanism responds powerfully to any incipient variation of current in the arc, the regulating mechanism by itsV quick action thus checking any tendency to further current variation in the arc. By the use or" a regulating mechanism having the functions described the arc will be maintained with a relatively larger difference of potential than is possible where a more sluggish and less powerful regulating mechanism is employed.

The particular mechanism which I use to obtain the results above generally outlined consists, briefly, of a movable coil operatively connected to one of the electrodes of thelamp, this coil being arranged so as to be acted upon by the field of a powerful inductance-coil. The movable coil and the inductance-coil are connected in parallel with each other and carry the current which passes through the arc.

the movable coil depends upon the product of the current therein and the iield of the inductance-coil in which it is placed, it will be evident that since the current variation in the movable coil is in much greater proportion than that of the main current a mechanical action exceedingly prompt and vigorous resented by a projecting pivot 5.

will take place upon the occurrence of any momentary fluctuation in the main current, which mechanical action decreases to a normal amount after the currents have again become steady.

It will be evident that my invention may be embodied in a wide variety of mechanisms without-departing from the spirit thereof. For purposes 0f illustration I have in the acl companying drawings illustrated two diierent ways in which the invention may be applied. The features of novelty which characterize the invention I have attempted to point out particularly in the appended claims.

In the drawings, Figure 1 represents one embodiment of my invention, and Fig. 2 a modified form of the same.

In Fig. l the inductance-coil above referred to consists of a magnetic core l, having a nearly-closed magnetic circuit, upon which core are mounted the two coils 2 3, constituting the winding of the inductance-coil, these coils being connected in series, as indicated. Between the opposed lower ends of the core l is mounted a movable coil 4. This movable coil in thepresent instance is arranged to rotate about an axis, one end of which is rep- For clearness of illustration the hearings for thedmovable coil and its support are not indicated. To make a better magnetic circuit fo'r the inductance-coil, abody 5, of magnetic material, is carried by supports 6 7, fixed to the lower ends of the core l and arranged so that it is within the coil 4 and between the two opposing lower ends of the core l. The two sides of the coil 4 therefore move within lthe respective air-gaps formed between the ends of the core l and the body 5', of magnetic material. By this arrangement the field due to the inductance-coil is very intense.

A suitable mechanical connection is made between the movable coil -iaud one of the electrodes of the lamp by which motion may be communicated from the coil to said electrode. In the present instance this connection consists of a projecting arm 8,movable with ther coil 4 and pivoted to the clutch mechanism 9, operating upon the upper electrode or carbon 10 of the lamp, the lower carbon or electrode being indicated at 1l. A dash-pot 12, having IOO one of its members pivoted to the arm 8, acts to prevent too violent motion of the same.

The movable coil 4 and the windings 2 3 of the indnctance-coil are connected in parallel with each other, as shown. The movable coil being of comparatively high resistance and of lowinductance, or, in other words, having a small time constant, practically carries what may be termed the fluctuating component of the main current. When this main current is steady, the component through the movable coil is comparatively small. The dynamic action of the coil is, however, considerable, due to the intense magnetic field of the inductance-coil, in which magnetic field the coil acts. When the main current fluctuates even slightly, a very large percentage variation of current occurs in the movable coil. The resulting momentary dynamic action between the movable coil and the field in which it acts is therefore momentarily much larger in proportion than the variation of the main current. The correcting action demanded of the regulating mechanism of the lamp is therefore temporarily very large and instantly corrects the incipient current variation to which it is due. The arc is thereby rendered more stable than would be the case with a less powerful and active regulating mechanism. The point at which the arc becomes unstable being thus raised, a larger proportion of the impressed voltage is usefully employed in the arc, and the efficiency of the same is increased.

Fig. 2 shows a modified arrangement of the arc-controlling mechanism, the principal feature of which is that the movable coil instead of having an oscillatory motion about an axis is arranged to have a straight-line motion. The core 13 of the inductancecoil is something the shape of a letter E, the winding 14 thereof being placed about the tongue 15. The movable coil 16 is arranged so as to surround the lower end of the tongue 15 and isdmoyable longitudinally along the same. TllearmsY of the core 13 extend downwardly and inwardly toward the lower end of the tongue 15, and the coil 16 is arranged so as to move in the field between the lower end of the tongue 15 and the opposing ends of the downwardly-projecting arms of the core 13. The winding 16 is mechanically connected with the clutch-carrying member 17 of the lamp. The clutch carried by this member is indicated at 18 and acts upon the upper carbon or electrode 19, the lower electrode being indicated at 20. The circuits of the lamp are substantially the same as those indicated in Fig. 1, the coils 14 and 16 being connected in parallel to each other and arranged to carry the current which Hows through the arc formed between the electrodes 19 and 20. The action of the mechanism is substantially the same also as that described in connection with Fig. 1, and further reference thereto is therefore unnecessary.

What I claim as new, and desire to secure by Letters Patent of the United States, is

l. In a regulating mechanism for an electric-arc lamp, the combination of an inductance-coil provided with a nearly-closed magnetic circuit, a movable coil mounted so as to be acted upon by the field in the open portion of the said magnetic circuit, electrical connections joining in parallel the said movable coil and the winding of said inductance-coil, anda clutch mechanism operatively connected to said movable coil.

2. The combination with the feeding mech anism of an arc-lamp, of parallel-connected relatively movable coils one of which is operat-ively connected to said feeding mechanism and mounted so as to be acted upon by the field due to the other and connections whereby both coils are traversed by current flowing through the arc.

In an electric-arc lamp, the combination of two coils of different time constants connected in parallel with each other and arranged so that one coil is acted upon dynamically by the other, a clutch mechanism, and operative connections between one of said coils and said clutch mechanism.

4. In an electric-arc lamp, the combination of two coils of different time constants connected in parallel with each other, a feeding mechanism, and operative connections between said feeding mechanism and the coil having the lower time constant.

5. In an electric-arc lamp, the combination of a fixed coil mounted upon a core of magnetic material, another coil with its terminals connected to the terminals of the first and mounted within the field due thereto and movable relatively to the first coil, a feeding mechanism, and operative connections between said mechanism and the movable coil.V

In witness whereof I have hereunto set my hand this 21st day of October, 1901.

ELIHU THOMSON.

Witnesses:

DUGALD MCK. MCKILLOP, HENRY O. WESTENDARP. 

